Water quality is periodically tested, for example to provide an indication of whether or not sea water is contaminated at beaches, and hence whether or not it is safe for bathing or undertaking other leisure activities such as surfing, body boarding, sailing, etc. The water quality tests are typically conducted by taking samples of water and undertaking testing under laboratory conditions. The tests monitor water quality by looking for the presence of faecal bacteria in the water, and usually involve producing cultures from the samples. Consequently, there is a delay of, typically, at least 24-48 hours before the test results are available. The test results are thus retrospective, providing an indication of the water quality at the time that the samples were taken, but only subsequently providing the results. Furthermore, the tests are typically only conducted on a periodic basis, and relate only to the precise location from which the sample was taken.
Given that the water quality at a given location can change rapidly, depending upon a number of factors including rainfall and other environmental conditions, such tests are of limited use in providing an indication of the current suitability of the water for undertaking various activities.